826 GEOKGE R. MINOT AND ARLIE V. BOCK 



in order to restore a sufficient number of platelets to prevent spontaneous 

 bleeding. It is, however, probable that other elements in the blood assist 

 to check a hemorrhage particularly associated with a deficiency or a defect 

 in the platelets. 



The duration of the life of the platelets is but a few days in contrast 

 to the longer life of the red corpuscles. Thus if a patient does not make 

 up some of his platelet deficiency within 3 to 5 days following a trans- 

 fusion for such a defect, one must anticipate a recurrence of the spon- 

 taneous hemorrhage. Hence further transfusion will be necessary if it is 

 desired to continue to check the bleeding. In hemophilia, in contrast to 

 the various forms of purpura hemorrhagica, hemorrhage is not spontaneous 

 but follows as a result of trauma, though this may be exceedingly slight. 

 In order to check a severe hemorrhage in hemophilia, enough blood should 

 be given to reduce the clotting time of the patient's blood to approximately 

 normal. By means cf such a procedure, hemorrhage is checked and thus 

 the bleeding point allowed to close. Later, as the transfused platelets 

 disappear from the circulation, the clotting time of the hemophiliac's blood 

 again becomes abnormally prolonged. Hemorrhage does not recur unless 

 the external or internal wound has not healed sufficiently. Hemorrhage 

 will of course recur when there is sufficient further trauma. Transfusion 

 may also be undertaken in hemophilia to prevent bleeding when operation 

 has to be performed. Under such conditions it may be desirable to remove 

 some blood before the normal blood is injected. 



In Table II is shown the effect of transfusion on the blood of a hemo- 

 philiac in whom rather severe bleeding was to be anticipated from the 

 extraction of teeth, if no normal blood had been given. 



The foreign blood, with its normal platelets, held the clotting time of 

 the patient's blood, with its qualitatively defective platelets, close to 

 normal for enough time to permit primary healing of the wound. 



In hemorrhagic disease of the newborn, the effect of transfusion is, 

 in a very high percentage of the cases, very striking, for here it seems 

 that normal blood is capable of doing more than tiding a patient over a 

 critical period. Following adequate transfusion in such cases there nearly 

 always occurs a permanent correction of the blood defect which is associ- 

 ated with a prolonged coagulation time and prothrombin time. To ac- 

 complish this result it may be necessary to give several doses of blood, 

 but frequently 40 c.c. suffices. 



In other conditions in which pathologic hemorrhage occurs due to 

 recognized or unrecognized blood defect, the principle outlined above 

 applies, namely, that if transfusion is to be used, enough blood, which will 

 furnish all the factors for coagulation^ must be given to accomplish the 

 desired result. 



4. The Effect upon Blood Kegeneration. When the bone marrow 

 is functioning deficiently, an increase in its regenerative activity often 



